Next time you go to your gym take a look at who is at the squat rack squatting. Most of the time in many public gyms you will notice that not too many people are squatting. Why you might ask? It could be because it takes a lot more effort than a leg extension, but it would do a lot more for the average trainee. The squat done properly works the big leg muscles like the hamstrings, quadriceps, upper back muscles, and lower back muscles. The fact that the squat work so many muscles would make it one of the most effecient exercises in the gym for the average trainee which has time constraints.
It makes sense to me to work as many muscles with one exercise as opposed to doing five different exercises and risk being overtrained. The problem is most gym goers have been tricked into thinking they can just follow the same long routines that are done in the muscle magazines. You know, the routines that say do 5 different exercises for chest and 5 different exercises for your shoulders. These routines end up disappointing many because they are not built for the average person trying to put on some muscle, they are built for genetically gifted and chemically enhanced body builders.
The fact is the people that spend the most time in the squat rack squatting are the people with the most muscle on the average in the gym. If you don't believe me next time you go to your gym make sure that you look at those that sit there and ride the bike all day compared to those that are the squat rack. I guarantee you the squat guy will win hands down. Now that you are seeing the benefits of the squat don't just go in there and do 4x20. I would start with 3x6 and work on perfecting the form, increasing weight by 5% if the form is perfect, and vary your reps when you have done them for about 3-4 weeks. Also, if you are a beginner I would do the squats more than 2 a week.